The present invention relates generally to an adjustable collimator for mammography and, more particularly, to an adjustable collimator for use with different size and shaped female breasts which minimizes fogging problems in the x-ray film due to secondary radiation and which eliminates the possibility of radiation scattering to tissue other than breast tissue.
Mammography is the x-ray technique used to detect and diagnose anomolies of the female breast including, for example, cancerous lumps or nodules. As the field has developed in recent years and newer and more advanced techniques have been implemented, a frequent, reoccurring problem is how one can utilize a standard mammography x-ray unit to accommodate a wide variety of breasts of varying size and shape. Typical mammography units described, for example, in U.S. Pat. No. 3,824,397, which issued to M. Bauer et al. on July 16, 1974, and U.S. Pat. No. 3,609,355, which issued to K. Schwarzer on Sept. 28, 1971, use an x-ray source which is collimated for mammography.
A collimating device is generally provided to restrict the x-rays to the breast. The collimator is designed to fit closely over the breast and to rigidly confine the x-rays within it to prevent scattering with resultant possible radiation damage to other parts of the patient. Additionally, the collimator functions to prevent secondary radiation which can fog the x-ray film. As such, it is very important that the collimator fit very closely and even tightly against the breast to prevent leakage and/or the introduction of secondary radiation and yet include the entire breast in the x-ray.
The problem presented here is that there are many different size and shaped breasts and a collimator which fits tightly against one may not fit as well against another. Accordingly, this has, heretofore, necessitated the stocking by a physician or x-ray laboratory of a number of collimators of different sizes and shapes which could be interchangeably mounted on a standard mammography machine. This has, as can be expected, resulted in an increased expense and a storage problem for the physician or laboratory as well as increasing the time required to perform the mammography since a particular breast would first have to be sized and an appropriate sized and shaped collimator would then have to be selected and mounted.
Attempts have, heretofore, been made to provide adjustable collimators for x-ray applications other than for mammography. For example, U.S. Pat. No. 3,448,270, which issued to L. Peyser on June 3, 1969, teaches an x-ray collimator having a plurality of pivotably movable shutter elements arranged in pyromidal fashion. Similarly, U.S. Pat. No. 3,609,370, which also issued to L. Peyser on Sept. 28, 1971, is directed to a collimator having a number of shutter elements or leaves. Neither of these collimators, however, is readily adaptable for use in mammography and both require extensive apparatus to effect re-adjustment of the cone.
Against the foregoing background, it is a primary objective of the present invention to provide an adjustable collimator to accommodate virtually any size and shaped breast.
It is another objective of the present invention to provide an adjustable collimator for mammography which can be used in conjunction with conventional mammography machines.
It is still another objective of the present invention to provide an adjustable collimator which is resistant to jamming and which can be easily readjusted to a different size.
It is yet another object of the present invention to provide an adjustable collimator which prevents leakage of x-rays.